Add unit tests for webroot permissions handling
Add unit tests for webroot permissions handling

Tested, pass.

lmcro/letsencrypt,brentdax/letsencrypt,bsmr-misc-forks/letsencrypt,bsmr-misc-forks/letsencrypt,jtl999/certbot,jsha/letsencrypt,jsha/letsencrypt,lbeltrame/letsencrypt,letsencrypt/letsencrypt,martindale/letsencrypt,martindale/letsencrypt,twstrike/le_for_patching,stweil/letsencrypt,Sveder/letsencrypt,xgin/letsencrypt,dietsche/letsencrypt,letsencrypt/letsencrypt,piru/letsencrypt,goofwear/letsencrypt,mrb/letsencrypt,wteiken/letsencrypt,VladimirTyrin/letsencrypt,TheBoegl/letsencrypt,thanatos/lets-encrypt-preview,mrb/letsencrypt,xgin/letsencrypt,VladimirTyrin/letsencrypt,mitnk/letsencrypt,TheBoegl/letsencrypt,dietsche/letsencrypt,kuba/letsencrypt,thanatos/lets-encrypt-preview,mitnk/letsencrypt,stweil/letsencrypt,lmcro/letsencrypt,lbeltrame/letsencrypt,Sveder/letsencrypt,twstrike/le_for_patching,brentdax/letsencrypt,goofwear/letsencrypt,DavidGarciaCat/letsencrypt,kuba/letsencrypt,piru/letsencrypt,jtl999/certbot,wteiken/letsencrypt,DavidGarciaCat/letsencrypt